1) Field of the Disclosure
The disclosure relates generally to methods and systems for analyzing composite structures, and more particularly, to methods and systems for determining and verifying ply orientation of composite laminates used in composite structures, such as aircraft composite structures.
2) Description of Related Art
Composite structures may be used in a wide variety of applications, including in the manufacture of aircraft, spacecraft, rotorcraft, watercraft, automobiles, and other vehicles and structures, due to their high strength-to-weight ratios, corrosion resistance and other favorable properties. In particular, in aircraft construction, composite structures may be used to form the tail sections, wings, fuselage and other component parts of the aircraft.
Composite laminates used to form composite structures may be manufactured by laying up or stacking multiple layers or “plies” together and curing the lay-up. A single layer or ply typically consists of reinforcing fibers in a matrix material. The composite laminates may be stacked with plies of different ply orientations in a defined sequence per design and/or quality requirements to optimize performance, such as load-carrying capacity. For example, the ply orientations may typically include 0° (zero degree) ply orientation, 90° (ninety degree) ply orientation, +45° (plus forty-five degree)/−45° (minus forty-five degree) ply orientation, or another suitable ply orientation. Determining the ply orientation of the composite laminates is important in optimizing composite laminate designs, as well as in complying with composite laminate design and/or quality requirements.
In addition, during the composite laminate manufacturing process, inconsistencies may occur during the lay-up or stacking of the plies, such as, for example, misoriented plies, gaps, overlaps, or other inconsistencies. Methods and systems for determining and verifying ply orientation may be used to analyze the composite laminates for any possible inconsistencies and to ensure that the composite laminates manufactured by the lay-up or stacking process meet the design and/or quality requirements pertaining to ply orientation.
Known methods and systems for determining and verifying ply orientation exist. However, such known methods and systems may require an extensive and time consuming polishing process of an edge or portion of a sample composite laminate to be analyzed. Such polishing process may be needed to obtain sufficient visibility of the fiber orientation of the composite laminate plies. The polishing process may require mounting the sample in an epoxy resin material, or a similar material, so that the sample may be secured in place during the polishing process. Such mounting process may be difficult with large samples that require polishing.
Further, such known methods and systems for determining and verifying ply orientation may require the use of a high magnification microscope, i.e., 100x or greater, to observe the individual fibers of the composite laminate plies of the sample. If the sample to be analyzed is larger than the field of view of the microscope, this may require obtaining multiple images of the composite laminate plies and editing the images together with a known photo editing software to obtain a continuous view of the sample under the microscope. This image preparation process may be time consuming and labor intensive.
Moreover, such known methods and systems for determining and verifying ply orientation may require additional cutting, polishing, and image processing steps to analyze fibers of the sample composite laminate having a +45° (plus forty-five degree) ply orientation and a −45° (minus forty-five degree) ply orientation. To sufficiently distinguish between a +45° (plus forty-five degree) ply orientation and a −45° (minus forty-five degree) ply orientation, a second cut of the sample composite laminate may need to be made and the processes of mounting, polishing, and image processing may need to be performed for both cuts of the +45° (plus forty-five degree) ply orientation and the −45° (minus forty-five degree) ply orientation. The additional work needed to analyze +/−45° (plus/minus forty-five degree) plies may increase the overall time and costs of manufacturing.
Thus, such known methods and systems for determining and verifying ply orientation may be very time consuming, labor intensive, and tedious, and may, in turn, result in increased manufacturing time and costs. For example, a known process for determining and verifying ply orientation that includes mounting, polishing, and image processing steps may take several days to complete.
Accordingly, there is a need in the art for an improved method and system for determining and verifying ply orientation of a composite laminate that provide advantages over known methods and systems.